LONDON — For the first time in nearly two years, the leaders of seven of the world's wealthiest democracies will meet to try to tackle some of the biggest global problems, including the post-pandemic recovery, climate change and the challenge of China. The three-day meeting of the Group of 7, hosted by the United Kingdom, will open on Friday in Carbis Bay, a seaside resort in Cornwall in southwest England.President Biden, who arrived in the U.K. Wednesday on his first overseas trip since taking office, has big goals of his own: to reestablish U.S. global leadership and repair old friendships in the wake of the Trump years.During his time in the White House, former President Donald Trump famously criticized America's democratic allies — "the European Union is a foe," he claimed — and sometimes praised its authoritarian rivals, including Russia, which was kicked out of what was then the G8 in 2014 for annexing Crimea.In Cornwall, Biden will strike a completely different tone."I know the past few years have strained and tested our transatlantic relationship, but the United States is determined, determined to reengage with Europe," Biden said in February, addressing the Munich Security Conference.Polls show that Biden's rhetoric and policy changes, such as rejoining the Paris Climate Accord, have boosted America's image in parts of Europe. A Morning Consult poll last month showed that attitudes toward the U.S. in Germany, France and the United Kingdom have rebounded since the Jan. 6 assault on the U.S. Capitol. But many Europeans remain skeptical of an American political system they once trusted, with majorities in Germany, Sweden, Austria and the Netherlands telling pollsters in April it was completely or somewhat broken.Analysts in Europe say Biden must now reach substantive agreements with G7 countries if he hopes to persuade leaders that, as he has said, "America is back.""We're beginning to ask ourselves questions along the lines of 'it's all very well and good that we love each other so much, but what is it that we're actually able to do together?'" says Nathalie Tocci, director of the Italian Institute of International Affairs in Rome and a special advisor to the European Union's chief diplomat, Josep Borrell. "It's going to be important in the context of the G7 for there to be an agreement on something."G7 finance ministers did agree earlier this month to a global minimum corporate tax of at least 15%, which critics say is too low. But this weekend they'll also set their sights on the pandemic, which is grinding well into its second year.Earlier this week, UNICEF urged the G7 members — the U.S., Britain, France, Canada, Germany, Italy and Japan — to send 20% of their vaccine doses to poorer nations in August or risk wasting them. The gap in vaccination rates between many wealthy and poorer countries is staggering. The U.K. says it has fully vaccinated more than 41% of its population, while Nepal reports a vaccination rate of about 2.5% percent.President Biden is set to announce Thursday that the United States has bought 500 million doses of the Pfizer vaccine to donate to COVAX, which is distributing vaccines to countries that cannot afford to buy enough shots.Britain says it intends to send doses abroad, but Health Secretary Matt Hancock said last week that vaccinating children at home is still the priority.Rob Yates, who runs the Center for Universal Health at Chatham House, the London policy institute, says G7 countries need to share more vaccines with developing nations, help fund more factories for vaccine production and encourage drug companies to share technological know-how to help countries in need."If the G7 is going to be serious about global leadership, we need to be taking a whole of humanity perspective and really valuing the lives of people in South Asia and sub-Saharan Africa like our own," says Yates. "This is going to require a massive effort."If the G7 doesn't step up, he warns, the developing world will become "exasperated" and will look to other countries for vaccines, such as Russia and China, the West's authoritarian rivals.The G7 has already made progress on another big issue: climate change. Last month, environment ministers agreed to climate targets to limit the rise in global temperatures to 1.5 degrees Celsius above pre-industrial levels — more ambitious than the previous 2-degree ceiling."This is a really big deal," says Samantha Gross, who runs the Energy Security and Climate Initiative at the Brookings Institution.Technological advances have reduced wind, solar and battery costs, she says, making the lower temperature target possible and making it easier to take more carbon out of the electricity generation process. More action at the G7 this weekend could provide momentum for change at two other global meetings this fall, she says: the G20 — the 20 countries which produce the vast majority of the world's GDP — which will gather in Rome in October, and the United Nations Climate Change Conference in Glasgow in November."If the entire G20 got on board, you would cover the vast majority of the world's emissions," Gross says.The G7 is a magnet for protests, and this year will be no different. Sculptor Joe Rush has built a replica of Mount Rushmore in a location visible from the G7 venue, in which he renders the faces of the G7 leaders — UK Prime Minister Boris Johnson, Japan's Prime Minister Yoshihide Suga, French President Emmanuel Macron, Italy's Prime Minister Mario Draghi, Canadian Prime Minister Justin Trudeau, German Chancellor Angela Merkel and Biden — with electronic waste, including keyboards and hard drives. Rush calls it "Mount Recyclemore" and wants to highlight the damage society does by the way it disposes of electronic devices.Extinction Rebellion, a global environmental movement which began in a town in England's Cotswolds, plans to stage marches to expose what it sees as the hypocrisy of rich countries' and corporations' pledges to reduce greenhouse gases. British farmers also plan to take to the streets to protest a free trade deal with Australia that they fear will lead to a flood of cheap food imports.Another expected topic of discussion at this weekend's summit is cyber security. In just the last month, cyber criminals have staged disruptive "ransomware" attacks on the world's largest meatpacking company and the biggest U.S. fuel pipeline. Christopher Painter, who served as the top U.S. cyber diplomat at the State Department, says G7 countries need to impose heavier political and economic costs on nations that allow hackers to launch attacks from within their borders."Countries can work together to use all their tools to try to pressure countries like Russia, either when Russia itself is doing it as a state-sponsored activity or when Russia is harboring these cyber criminals," he says.The other big issue in Cornwall will be China, which poses the greatest challenge to the West in decades.President Biden needs partners to help confront Beijing on everything from unfair trade practices and intellectual property rights to the country's increasing assertiveness in the South China Sea and threats toward Taiwan.Backed by the world's second-largest economy, Chinese Communist Party General Secretary Xi Jinping argues that Beijing's authoritarian model is an effective alternative to liberal democratic systems. Biden has called this an "inflection point" for democracy. The European Union has cooled to China in recent months, but shows no interest in joining the U.S. in an anti-China bloc.Critics complain that G7 meetings are long on statements, which are often quickly forgotten, and short on collective action. But this time, in the face of a once-in-a-century pandemic and a narrowing window to tackle climate change, there may be more pressure to act. Copyright 2021 NPR. To see more, visit https://www.npr.org.